Optimizing dredging waste sediment in cementitious composites using layered double oxides: Effects on mechanical behaviour, durability, and microstructure

To improve dredging waste sediment (DWS) usage, Portland cement (PC) and ground-granulated blast-furnace slag (GGBFS) are employed as the curing agent in this study to examine how varying doses of layered double oxide (LDO) affected the setting time, flow, mechanical strength, freeze resistance, waterproofness, ionic adsorption, hydration, micromorphology, and pore structure of the binary composite matrix. The hydration products and pore distribution are further analyzed and characterized using IC, TG-DTG, SEM, and MIP methods. The results indicate that the increase in DWS substitution decreases the actual volcanic ash cementing activity, resulting in a decrease in mechanical properties. Nevertheless, the compressive strength of DWS60 can still reach 8.2 MPa after 28 days. The large surface area and high viscosity of DWS particles prevent flow extension and increase the coagulation time. The LDO that uses a 0.6 % dose have the most effective effect on improving their compressive strength, with a 14.6 % increase in strength over 28 days. Moreover, LDO can enhance early hydration to shorten the hardening period of the pastes. The frost resistance of the structure is enhanced by the filling effect of LDO particles and hydration nucleation. The laminar structure of LDHs allows dangerous heavy metals, such as Cu and Cr ions, to solidify due to their high ion exchangeability. The TG and the MIP found that it contributes to the generation of C-(A)-S-H and AFt phases and strengthens the mechanical properties by optimizing the pore structure. A comprehensive evaluation of the various properties and costs of the samples containing DWS and LDO concluded that the fabricated structures are compatible with some low requirement building construction elements. These outcomes are expected to suggest engineering recommendations for the application of DWS. •Dredging waste sediment cured by cement and blast furnace slag is investigated.•Various dredging waste sediment content and layered double oxide dosages are explored.•LDOs exhibit good heavy metal adsorption capacity due to their interlayer effect.•Adding LDO compensates for the paste's slower early compressive strength increase.•LDOs improve pore size distribution and heal cracks by filling structural pores.